Beware Registered Voter Surveys In 2014

October 22, 2013

A wave of new surveys shows that the shutdown took a toll on the Republicans, but less clear is whether it's enough to endanger the GOP House majority. Last night, two surveys from CNN and ABC/Washington Post showed Democrats building an 8 point lead on the generic ballot; if Democrats could win the popular vote by such a wide margin, they would be well positioned to retake the House. But those 8 point leads might not be as strong as they look.

These are polls of registered voters, not likely voters. And once the pollsters apply likely voter screens, the Democratic edge will narrow. Check out how this month's post-shutdown surveys contacting voters with a cell phone fared over the last four congressional elections.

In both 2010 and 2006, polls of registered voters significantly overestimated the Democrats. There's a good reason: non-white and young voters, who disproportionately support Democratic candidates, are also disproportionately likely to stay home during low turnout, midterm elections.

In 2010, the application of likely voter screens turned a tight race into a Republican rout. Pew Research's 1 point Democratic edge among registered voters, for instance, became a 6 point Republican lead among likely voters. Perhaps turnout will be a little better for Democrats in 2014, but it seems unlikely that Democrats will completely defy history and retain the entirety of their advantage among likely voters.